Allied to this animal, and apparently still nearer to the American Bison, is the extinct _B. priscus_ of Europe. The Pleistocene Bisons of North America, _B. antiquus_ and _B. latifrons_, are not remote from the living forms. Finally, the Miocene _B. sivalensis_ from India, and the Pliocene _B. ferox_ and _B. alleni_ of North America, take back this group to as remote a period as any other genus of Oxen. {320} [Illustration] FIG. 168.--Yak. _Bos grunniens._ x 1/15. [Illustration] FIG. 169.--British Wild Ox. _Bos taurus._ From Vaynol Park, Bangor. x 1/20. The Yak, _Bos grunniens_, is a long-haired peculiar type, confined to the Thibetan plateau. _B._ (_Anoa_) _depressicornis_ of Celebes is characterised by its straight horns; allied to it is _B. mindorensis_ (Philippine Islands), supposed, however, to be a hybrid between {321} it and some other species. Africa has at least two Buffaloes. We may finally mention the Wild Ox of Europe, _B. primigenius_, the supposed progenitor of our domestic cattle, believed to be still surviving in the herds at Chillingham, Chartley, and elsewhere. This animal is sometimes called the Aurochs. The Romans spoke of it as the Urus, and it appears to have formerly attained to more gigantic proportions than at present. It is the small size of the present race that is the chief objection to tracing them back to the large Oxen existing near London in 1174, and found sub-fossil in the Cambridgeshire fens. [Illustration] FIG. 170.--Punjab Wild Sheep. _Ovis vignei._ x 1/10. Of the true sheep, genus _Ovis_, there are a considerable number of species. The Sheep are to be distinguished from the Goats by their rather stouter build and by the absence of the beard in the male. The horns are developed in both sexes, and are usually twisted and often of large size. The Sheep are almost entirely Palaearctic and Nearctic. They only just get into the Oriental region. One of the finest species is the great Pamir Sheep, _O. poli_, whose length reaches 6 feet {322} 7 inches, and height 3 feet 10 inches. The horns of this fine Sheep may measure more than five feet round the curves. The Rocky Mountain Bighorn (_O. montana_) is a Sheep ranging along the Rockies as far south as New Mexico, and also to the far north; they are not confined to the chain of mountains mentioned, but occur also on the mountains of British Columbia down to those of California. The horns are not quite as large as those of the last species, but measurements give a length (along the curve) of 32 to 40 inches. [Illustration] FIG. 171.--Himalayan Burrhel Sheep. _Ovis burrhel._ x 1/12. (From _Nature_.) [Illustration] FIG. 172.--Blanford's Sheep. _Ovis blanfordi._ x 1/10. (From _Nature_.)